plant responses
DESCRIPTION
PLANT RESPONSES. Do plants have minds?. ??? Read the article and decide for yourself. Do plants have stress? Do they respond?. What are some abiotic stresses faced by plants?. *Turn to a partner & list some abiotic stresses faced by plants*. Abiotic Environmental Stresses. - PowerPoint PPT PresentationTRANSCRIPT
PLANT RESPONSES
Do plants have minds?
???Read the article and decide for yourself
Do plants have stress? Do they respond?
What are some abiotic stresses faced by plants?
*Turn to a partner
& list some
abiotic stresses faced by plants*
Abiotic Environmental Stresses
-temperature (too hot, too cold)-amount of sunlight (too much, too little)-water availability (too much, too little)-lack of nutrients in soil-others you came up with??
What are some biotic stresses faced by plants?
*Turn to a partner
& list some
biotic stresses faced by plants*
Biotic Environmental Stresses
• predators (omnivores/herbivores)• disease (caused by bacteria, fungi,
viruses and/or animals)• competition with other plants• others you came up with??
How do plants deal with these stresses?
ADAPTATIONS!
Tropisms
Tropisms
A tropism is “the turning of all or part of an
organism in a particular direction in response to an external stimulus.”
It is derived from Greek tropos meaning “turning”
Tropisms Can be Positive or Negative
If a plant turns towards the stimulus, then it is a
positive tropism.
If a plant turns away from a stimulus, then it is a
negative tropism.
Phototropism
Phototropism is “the orientation of a plant or other
organism in response to light, either toward the source of light (positive phototropism) or away
from it (negative phototropism).”
Positive Phototropisms
Stems exhibit positive
phototropism when leaning towards light
Negative Phototropisms
http://leavingbio.net/Plant%20Responses.htm#tropisms
Roots exhibit negative
phototropism when growing away from the
light
Gravitropism
Gravitropism is “the growth of a plant or other
organism in response to gravity, either being pulled down by gravity (positive
gravitropism) or growing against it (negative gravitropism).”
Positive Gravitropism
Roots exhibit positive
gravitropism when growing down towards
gravity
Negative GravitropismStems & leaves exhibit
negative gravitropism
when growing up
against gravity
Thigmotropism
Thigmotropisms are growth responses to touch
Positive Thigmotropisms
Plant stems (tendrils) exhibit positive
thigmotropism when they coil around an object.
Venus fly traps exhibit positive thigmotropismwhen they snap shut at the touch of an insect
landing inside
Negative ThigmotropismsRoots exhibit negative thigmotropisms when they grow away from or around
an object in the soil